code: def paintEvent(self, event):
      width = int(self.device_pixel_ratio * self.width())
      height = int(self.device_pixel_ratio * self.height())
      if (width, height) != self._renderer.get_canvas_width_height():
          surface = cairo.ImageSurface(
              cairo.FORMAT_ARGB32, width, height
          )
          self._renderer.set_context(cairo.Context(surface))
          self._renderer.dpi = self.figure.dpi
          self.figure.draw(self._renderer)
      buf = self._renderer.gc.ctx.get_target().get_data()
      if QT_API == "PyQt6":
          from PyQt6 import sip
  
          ptr = int(sip.voidptr(buf))
      else:
          ptr = buf
      qimage = QtGui.QImage(
          ptr,
          width,
          height,
          QtGui.QImage.Format.Format_ARGB32_Premultiplied,
      )
      # Adjust the buf reference count to work around a memory leak bug in
      # QImage under PySide.
      if QT_API == "PySide2" and QtCore.__version_info__ < (5, 12):
          ctypes.c_long.from_address(id(buf)).value = 1
      qimage.setDevicePixelRatio(self.device_pixel_ratio)
      painter = QtGui.QPainter(self)
      painter.eraseRect(event.rect())
      painter.drawImage(0, 0, qimage)
      self._draw_rect_callback(painter)
      painter.end()
  
file_path: matplotlib/lib/matplotlib/backends/backend_qtcairo.py
imports: import ctypes
  from .backend_cairo import cairo, FigureCanvasCairo
  from .backend_qt import _BackendQT, FigureCanvasQT
  from .qt_compat import QT_API, QtCore, QtGui
label_desc: Use image node_id 2 for calling the FigureCanvasQTCairo obj's underlying member method code with example usage: obj.paintEvent(event) without return types